Lec 5. Sex determination and sex linked characteristics Flashcards Preview

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Flashcards in Lec 5. Sex determination and sex linked characteristics Deck (31)
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1

What gene determines sex?

SRY gene

2

What protein determines sex?

TDF

3

How many pairs of chromosomes do platypus's have?

5 pairs. 5 Xs 5Ys or 10Xs

4

What is heteromorphic?

X and Y are called heteromorphic

5

What is the primary testis initiation gene in therian mammals?

SRY

6

Define sexual reproduction

Alternates between haploid and diploid states

7

What does Fertilization produce?

a diploid zygote

8

What does Meiosis produce?

Haploid gametes

9

Define heterogametic

sex produces 2 different gamete types -with 2 different sex chromosomes

10

True or False? Most organisms have two sexual phenotypes, male and female.

True

11

Define Parthenogenesis

reproduction without males

12

In mammals, the X and Y chromosomes usually do what during meiosis?

pair even though they are not homologous

13

How many genes are on the Y chromosome?

around 30

14

How many genes are on the X chromosome?

more than the Y a lot.

15

What are autosomes?

Non-sex chromosomes.

16

What are the sex chromosomes for insects?

XX (f)-XO (m)

17

What are the sex chromosomes for birds and reptiles?

ZW (f) -ZZ (m)

18

What is the role of the X sex chromosome?

contains genetic info essential for both sexes. At least one copy of an X is required

19

What is the role of the Y chromosome?

male-determining gene is located here.

20

Where are the X and Y chromosomes only homologous in?

pseudoautosomal regions

21

In the Haplodiploidy system: Haploid set is

Male (unfertilized)

22

In the Haplodiploidy system: Diploid set is

Female (union of sperm and egg)

23

What is the genic sex-determining system and where is it found?

No sex chromosomes, only sex-determining genes. Found in plants, fungi, fish.

24

What is an example of environmental sex determination?

aquatic snail, limpets position in stack determines sex

25

What is another example of environmental sex determination?

Alligators temperature-dependent sex determination

26

what is the genotype for Turner syndrome?

XO. Females

27

What is the genotype for Klinefelter syndrome?

XXY, XXXY or XXXXY or XXYY. Males

28

What are the signs and symptoms of a person with Turner Syndrome?

Short, high arched palate, retrognathia, webbed neck, droopy eyes, lazy eye, broad chest

29

What are the signs and symptoms of Klinefelter syndrome?

After 5 years of age, boys are taller and fatter around belly, clumsy, slow motor skills.

30

In what way could the SRY gene not function?

Androgen-insensitivity syndrome